1. Technical Field
The invention relates to a projection zoom lens system having a six-group configuration and a projection type display apparatus having the projection zoom lens system. In particular, the invention relates to a projection zoom lens system configured to project and magnify onto a screen, rays which contain image information and are generated from a light valve such as a liquid crystal display device or a DMD (Digital Micromirror Device) display device, and a projection type display apparatus having the projection zoom lens system.
2. Description of the Related Art
Recently, beam projectors (projection display devices) using light valves such as transmissive or reflective liquid crystal display devices or DMD display devices have come into widespread use and have become sophisticated. Particularly, as a resolution of the light valves increases, a demand for improvement in resolution of the projection lens system has increased.
Furthermore, considering improvement in a degree of freedom at the time of setting a distance to a screen and installability in a small room, a demand for mounting a wide zoom lens system or a high-power zoom lens system having compactness and higher performance onto a projection type display apparatus has also increased.
To meet the demands mentioned above, JP 2003-337283 A has proposed the following projection zoom lens system. This zoom lens system is configured so as to improve an optical performance in the whole zooming range from a wide-angle end to a telephoto end by increasing the number of moving groups in the zoom lens system. However, there arise such problems that fluctuation of the spherical aberration accompanied by zooming is large and that a marginal ray tends to be largely under especially at the telephoto end.
Then, as described in JP 2005-84455 A, there has been proposed a projection zoom lens system configured to reduce fluctuation of the spherical aberration accompanied by zooming by providing a surface having a strong negative refractive power in a third lens group of the zoom lens system having six groups.
However, in the projection zoom lens system described in JP 2005-84455 A, fluctuation of the spherical aberration accompanied by zooming decreases, but a problem arises that the astigmatism increases.